River Tees Case Study

Case Study: The River Tees

Overview

The River Tees is a significant watercourse in the North East of England, stretching approximately 137 km from its source in the Pennines to its mouth at the North Sea near Middlesbrough. It drains an area of around 1834 km² and showcases classic river processes and landforms across its upper, middle, and lower courses. The River Tees is an excellent case study for examining how river characteristics change from source to mouth, including channel width, depth, velocity, and the formation of various landforms such as waterfalls, meanders, and oxbow lakes.

Upper Course

Location and Land Use

The River Tees originates at Cross Fell in the Pennines, at an elevation of about 750 meters. The upper course primarily consists of moorland, which is sparsely populated and used for sheep farming. Annual rainfall is high, exceeding 2000 mm in some areas, feeding into the river’s headwaters and contributing to a steep, fast-flowing stream.

River Channel and Valley

The river’s channel is narrow and shallow in the upper course, with large angular boulders on the riverbed. The steep gradient results in vertical erosion dominating the landscape, cutting deep valleys with V-shaped profiles. The river’s flow is turbulent due to the rough, uneven bed, and the high friction levels slow down the water despite the steep gradient.

Key Landforms

1. High Force Waterfall: One of the most prominent features of the upper course is High Force, the tallest waterfall in England, at 21 meters. It forms where a hard band of Whin Sill (igneous dolerite) overlies softer sandstone and limestone, leading to differential erosion. The softer rock erodes faster, creating an overhang that eventually collapses, forming a plunge pool at the waterfall’s base. Over time, the waterfall retreats upstream, leaving a gorge behind.
2. Interlocking Spurs: In this section, the river winds through hard rock, creating interlocking spurs as it erodes the softer rock in between.

Human Activity

Cow Green Reservoir, built in 1970, is the primary human intervention in the upper course. The reservoir was constructed to supply water to the growing industrial areas downstream, particularly Teesside.

Middle Course

Location and Land Use

As the River Tees moves downstream into the middle course, the landscape becomes less steep, and the valley widens significantly. This area, particularly around Barnard Castle, is more fertile and suitable for arable farming. Agriculture dominates the land use here, with productive floodplains developing due to alluvial deposits from the river.

River Channel and Valley

The river’s gradient decreases, causing lateral erosion to become more significant than vertical erosion. The river channel becomes wider and deeper, and the velocity of the water increases due to reduced friction from a smoother riverbed. The valley sides are less steep compared to the upper course.

Key Landforms

1. Meanders: The river forms large meanders in the middle course, especially near Barnard Castle. These meanders occur due to lateral erosion on the outer banks of the river bends and deposition on the inner banks.
2. Floodplains: The widening of the valley allows for the formation of flat floodplains, which are valuable for agriculture. During periods of heavy rain, the river can flood these areas, depositing nutrient-rich silt.

Human Activity

Agriculture is more prominent in the middle course, with farms utilising the fertile land along the river. The increased water volume due to tributaries joining the Tees also provides a stable water supply for irrigation and other uses.

Lower Course

Location and Land Use

In its lower course, the River Tees flows through low-lying areas, passing urban centres such as Yarm, Stockton-on-Tees, and Middlesbrough. Industrial and urban land use dominates this section, particularly around the Tees estuary, which serves as a hub for shipping, industry, and commerce. The lower Tees is also important for recreational activities and wildlife conservation.

River Channel and Valley

As the river approaches the sea, the channel becomes much wider and deeper. The river slows considerably as it meanders across a wide, flat floodplain. The river’s lower course is affected by tidal flows, with the Tees becoming partially tidal near Stockton-on-Tees. Humans have heavily modified the river to support navigation and control flooding.

Key Landforms

1. Meanders and Oxbow Lakes: The meanders in the lower course are much larger than those in the middle course. As erosion continues on the outer bends and deposition continues on the inner bends, some of these meanders have been cut off, forming oxbow lakes.
2. Levees: This section shows natural levees formed from repeated flooding and sediment deposition along the riverbanks. These levees help raise the banks and provide some natural flood protection.
3. Estuary: The mouth of the River Tees forms a large estuary with mudflats and sandbanks. These areas are critical habitats for birdlife and other species and are protected as part of various conservation efforts.

Human Activity

1. Tees Barrage: Built in 1995, the Tees Barrage controls the river’s flow to prevent flooding and support recreational activities. It also ensures the river remains navigable for shipping by maintaining a consistent water level upstream.
2. Mandale Cut: To improve navigation, an artificial cut bypassed a large meander known as the Mandale Loop, shortening the river by approximately 4 km.
3. Industrialisation: The lower Tees has been heavily industrialised, particularly around Middlesbrough, where the river supports large-scale steel production, chemical works, and port activities.